It is well known that photographic colour images can be obtained by treating an imagewise exposed silver halide material containing one or more colour couplers with a colour developing solution. Colour developing agent oxidised in the presence of silver halide development couples with the colour coupler to form a dye image.
In most such processes the image-bearing silver halide material is treated with a bleach solution which oxidises the silver image, often back to a silver halide, and a fix solution which removes the unexposed silver halide and silver salt formed by the bleach from the material. A combined bleach/fix solution is alternatively used.
In the desire to use less silver in photographic materials it has been proposed that low silver-containing silver halide materials can be processed by a redox amplification method whereby the dye is produced in the vicinity of very small amounts of silver image which acts as a catalyst.
There are problems in operating a redox amplification system concerned with the stability of the solutions used while low silver materials will not provide the desired Dmax for the images produced without a redox amplification process.